This invention relates to devices which depend upon accurate measurement of changes in the refractivity of a flowing fluid, e.g., in liquid chromatography.
Because temperature affects refractivity, the temperature of the flowing liquid must be carefully controlled.
Typically in refractive index detectors used in liquid chromatography the refractivities of sample and reference streams are compared at a cell. One technique for equalizing temperatures in the sample and reference streams in the cell has been to supply the fluid to the cell after having passed through sample and reference inlet tubes in heat-exchanging relationship with each other and with a large metal block. Ideally, both streams are at equal temperatures before entering the cell.